How to Replace a Bathtub

Replacing a bathtub looks like a single job — pull the old one out, set the new one in — but it is really a chain of a dozen smaller steps, and the ones that matter most are the ones you never see once the tub is in place. Done right, a tub swap is clean, durable, and invisible. Done in a hurry, it hides a slow drain leak or a flexing base inside a finished wall, where it does quiet damage for months before it shows up as a stain on the ceiling below.

At Oakwood Remodeling Group we do bathrooms and showers only, and this is one of the jobs we do most. Below is the honest, full sequence of how a bathtub replacement actually goes, step by step, with the DIY-difficulty and leak-risk of each stage called out plainly. If partway through you decide the job belongs with a licensed pro, our bathtub replacement and tub-to-shower service covers the whole thing. If you are still deciding whether to attempt it at all, read our companion guide on whether you can replace a bathtub yourself first — this page assumes you want to understand the process either way.

Before you start: know what you are dealing with

The difficulty of the whole job is set before you swing a hammer, by two things: the tub material and whether the plumbing has to move. A light acrylic or enameled-steel tub in a standard 60-inch alcove, with the drain staying exactly where it is, is the friendliest version of this project. A cast-iron tub, a tiled surround, or a moved drain each escalates it sharply. Most of the difficulty ratings below assume the friendly case — a like-for-like alcove swap — and note where the harder versions change the picture. For the alcove format specifically, our alcove bathtub guide covers the fixture in more detail.

The step-by-step process, start to finish

Here is the full sequence in order. Read it once all the way through before starting anything — the mistakes that cause leaks usually come from getting a step out of order or skipping the unglamorous ones.

1. Shut off the water and drain the lines. DIY difficulty: easy. Close the local stops if the tub has them, or shut off at the main. Open the tub faucet to bleed the lines and confirm the water is truly off. Skipping this is how a routine swap becomes a flooded bathroom.
2. Remove the tub door or shower rod and the lower surround. DIY difficulty: moderate; messy. Any glass door or track comes off, then the lower course of the surround — because it was installed down over the tub's flange and has to come off to free the tub. Expect dust, screws, and adhesive.
3. Disconnect the waste-and-overflow and the supply. DIY difficulty: moderate; leak-risk when reassembling. Under the tub's drain end, disconnect the waste-and-overflow assembly from the drain shoe and unhook the overflow. Access is often through a panel behind the tub wall or from a crawlspace or the room behind. This is the first of the hidden connections that must later seal perfectly.
4. Cut the caulk and free the tub's flange fasteners. DIY difficulty: moderate. Slice the caulk line at the tub deck and remove the nails or screws pinning the tub flange to the studs. The tub is now mechanically free — resist prying until every fastener and caulk seam is actually released, or you crack tile you meant to keep.
5. Remove the old tub. DIY difficulty: moderate for acrylic/steel, hard for cast iron. A light acrylic or steel tub lifts out whole with a helper. A cast-iron tub at 300-plus pounds is usually broken up in place with a sledge — heavy, loud work that is a real reason to hand a cast-iron job to a pro. Our cost-to-replace-a-bathtub guide breaks down how much that heavier removal adds.
6. Inspect the subfloor and framing. DIY difficulty: easy to look, harder to fix. With the tub out, check the subfloor at the drain end and the studs behind the surround. In mid-century Sacramento stock a slow surround leak often rots the subfloor here. Do not build on soft framing — fix it now, with the space open.
7. Repair the base and dry-fit the new tub. DIY difficulty: moderate. Cut back and re-sheet any bad subfloor, make the base level, then set the new tub in dry to confirm the drain lines up, the flange sits on the studs, and the tub is level end to end.
8. Set the mortar bed and place the new tub. DIY difficulty: moderate; skipping it is a top mistake. Trowel a mortar bed across the tub's footprint and lower the tub into it so the base is fully supported and does not flex. Fasten the flange to the studs. This step is why a good acrylic tub feels solid underfoot for decades.
9. Connect the drain, waste, and overflow — then water-test. DIY difficulty: hard; highest leak-risk. Seal the drain shoe with putty or a gasket, connect the waste-and-overflow, and seat the overflow gasket with no gaps. Then fill the tub and watch every joint before anything gets covered. This is the single most important step to get right — a leak here drips into the framing unseen.
10. Install the surround backer and waterproofing. DIY difficulty: moderate to hard; leak-risk at the flange. For a tiled surround, hang cement or foam waterproof backer and a membrane, lapping the waterproofing over the tub flange so water is directed into the tub, never behind it. For a panel system, follow the manufacturer's waterproofing detail. This joint between wall and tub is leak-risk point number three.
11. Finish the surround and set the valve trim. DIY difficulty: hard for tile, easier for panels. Tile and grout, or install the panels, and set the tub-and-shower valve trim — ideally on a new pressure-balanced valve you swapped while the wall was open. Grout and thinset need real cure time in our climate and cannot be rushed.
12. Caulk, cure, and inspect. DIY difficulty: easy to do, easy to do badly. Caulk the tub-to-surround joint and the deck with a quality silicone — leak-risk point number four. Let everything cure before use, and if the job was permitted, pass final plumbing inspection before the space goes back into service.

The four leak-risk points, in one place

Almost every tub-replacement failure traces to one of four spots. Knowing them tells you exactly where to slow down — and, if you hire out, exactly what to ask your contractor how they handle:

• The drain shoe. The seal under the tub where the drain body meets the tub. A gap here leaks straight into the subfloor and is completely hidden.
• The overflow gasket. At the head of the tub; a pinched or missing gasket weeps into the wall cavity every time the tub fills near the top.
• The surround-to-flange joint. Where the wall waterproofing meets the tub flange. If waterproofing does not lap over the flange, water runs behind the tub.
• The caulk line. The visible joint at the tub deck. The most forgiving of the four because you can see it fail, but still a maintenance point in Sacramento's hard water.

An honest word on when to call a pro

A like-for-like acrylic swap in a standard alcove, drain staying put, is genuinely within reach for a capable DIYer with a helper and a free weekend or two. If that describes your job and you are comfortable with the drain connection, attempting it is reasonable. But be honest with yourself about the three lines that separate a weekend project from a professional one: a cast-iron tub that has to be broken out, a tiled surround that has to be waterproofed correctly, or any moved plumbing that triggers a permit under the California Plumbing Code. Cross any of those and the job asks for skills and tools most homeowners do not have on hand.

The reason we push hardest on the hidden steps — the drain seal, the mortar bed, the waterproofing lap over the flange — is that they are exactly the steps that do not announce a mistake. A crooked tile is obvious the day you set it; a marginal drain seal looks perfect and then rots a subfloor over the following winter. In Sacramento's hard water and across our slab-on-grade and 1960s-to-1980s ranch stock, a waterproofing detail that is merely okay does not stay okay. That is the specific value a licensed pro adds: not the muscle, but the buried details that determine whether the tub is still dry in five years.

Whether you tackle it yourself or hand it off, an accurate estimate for the pro route starts with an in-home look, because the number hinges on the surround you want, whether the plumbing can stay put, and what is behind the walls. When we visit, we confirm the tub size and drain side, check the plumbing and framing, and walk you through the honest new-tub-versus-walk-in-shower decision for your bathroom. You leave with a clear, all-in line-item range — not a vague ballpark. As a 5.0★-rated, licensed Rocklin contractor (#1125321) backed by a 3-year workmanship and 10-year structural warranty, we would rather show you the real number than the low one.

Ready to replace that old tub — or thinking about a walk-in shower instead? Contact Oakwood Remodeling Group for an in-home estimate across Roseville, Rocklin, Sacramento, and the surrounding Placer, Sacramento, and El Dorado county communities. You can also explore our full set of bathtub replacement guides.